Fig. 2.

Stretch-evoked EMG activity of extraocular muscles Examples of stretch-evoked activity in 2 monkeys, m1 and m2 a–d and a rat, r2 e. The upper trace indicates the force applied to produce eye rotation (the upward deviation in the force trace resembles stretching of the lateral rectus muscle). The lower trace shows stretch-evoked EMG signals from this muscle. In a, d, the experimenter produced rhythmical eye rotations of about the same amplitude. In c, in the first cycle of eye rotation, the experimenter produced a regular-amplitude stretch, a smaller stretch in the second cycle and returned to regular-amplitude stretches in two subsequent cycles, resulting in respective modifications of SR responses in terms of EMG signals and forces. In d, the stretch was not reversed during about half a second, resulting in a prolongation of the stretch-related activity. e Rat stretch-evoked EMG responses were comparable to what was found in monkeys. Stretch reflex could be evoked repetitively and the amplitude of the response modulated with the intensity of the external force applied to rotate the eye